I've had dreams too, where loved ones appear and speak something and I can't remember what they said when I wake up. But I've done a lot of reading and research into dreams over the past 30 years, and I now firmly believe that we remember what we need to remember, that if we don't remember everything, it's because we don't need the messages or information yet. What I do is ask those people to come back into another dream and let me know what it is I most need to know from them.
I think our sub-conscious DOES remember whatever was good and beneficial from a dream and incorporates it into our psyche. I'm sure, MG, that's what has happened with you in this dream. You remembered the most important part of the message, but your sub-conscious will have retained the rest of the note but has for some reason determined that it's not essential for you to remember it right now.
The dreams that bother me so much are when I catch fleeting glimpses of them in the distance but can't find a way to reach them, and I spend the entire dream chasing after them. I always wake up so exhausted and disheartened after those dreams.
When you don't like a thing, change it.
If you can't change it, change the way you think about it.